This invention relates generally to external fixation devices and particularly to external fixation devices for restraining the head of a person having a neck or back injury. Still more particularly, this invention relates to external fixation devices for attachment to a person's skull by pins that penetrate into small holes drilled into the person's skull.
Cervical skeleton traction is used to treat the unstable spine, to treat signal fractures and to accomplish reduction of cervical facet dislocations. In the past, skeleton traction has been applied utilizing caliper-like devices and halo-type rings. Both types of devices use pins which are drilled or screwed through the scalp into the skull to allow force vectors to be applied to the skull and spinal structure.
Exemplary of the caliper devices of the prior art are the Crutchfield Tongs. This device has two arms fastened together in the shape of an "X" and is pivotable at the intersection of the two arms. At the scalp end of each arm, a pin is affixed for penetration into pre-drilled skull holes. At the other end of each arm, there is a threaded rod and thumb screw structure which, when operated, tends to force the pin ends of the tong arms together or apart in accordance with the direction in which the thumb screw was turned. These tongs are applied to the top of the head with one pin on each side of the longitudinal axis of the spine. The pins are roughly perpendicular to the scalp, but because the tongs do not reach down around the head to a point just above the ears, the angle of the scalp pins to the longitudinal axis of the spine is acute when viewed from the front or rear of the head. Accordingly, when tension is placed upon the Crutchfield Tongs, the angle of the pins is such that, if not tightly compressed by the thumb screw, it is possible to pull the Crutchfield Tongs completely out of the skull.
Only two pins are used in the Crutchfield Tongs. As a result, a pivot line was established between the contact points of the pivot points and the skull. Thus, flexion and extension of the skull in relation to the spine, i.e., tilting of thehead forward and rearward, was not possible with the Crutchfield Tongs. Further, traction using the Crutchfield Tongs confined the patient to bed such that ambulation was not possible.
Another example of caliper devices are Barton's tongs. The structure of Barton's tongs is similar to that of the Crutchfield device; however, the arms are longer such that the pins reach further down on the head toward the ear. The shape and length of the tong arms are such that the drills of Barton's tongs entered the skull horizontally at a point somewhere between the top of the head and the ear such that a 90.degree. angle is formed with the longitudinal axis of the spine. Barton's tongs have a greater resistance to pulling out of the skull than Crutchfield's tong, because of the increased angles of the pins with respect to the spine.
Another example of this type of device is the Gardner tongs, which have a different structure than the Crutchfield tongs and are less likely to loosen under prolonged traction load than are Crutchfield's tongs. Gardner's tongs include a semicircular frame structure in the approximate shape of a horseshoe with threaded pin holes on each end of the horseshoe arms. The horseshoe is placed down over the patient's head such that the pins contact the skull at a point just above the ears and in line with the longitudinal axis of the spine. Thus, the plane defined by the two pins and the point of contact of the tongs with the traction line passes through the center line of the spine. Excessive anterior placement of the tongs resulted in a forward tilt of the head resulting in misalignment of the spine. Since only two pins are used, a pivot line is formed and it is not possible to apply flexion and extension force vectors in the anterior-posterior plane with this device.
Anterior-posterior positioning of pins is disclosed in Russian Pat. No. 633,526. That patent discloses a tong-like device with facility for affixing two pins on either side of the head. This patent also discloses a plurality of holes centered at the top of the horseshoe and spaced above its center line. This feature plus the four points of contact with the skull allows the skull to be canted from left to right by placing the hook of a traction line to the left or right of the centerline of the horseshoe.
The inconvenience and attendant additional risk of confining a patient to bed during extended traction resulted in the development of the halo-type device. The halo-type device consists of a circular frame with an upturned portion in the rear with the frame completely encircling the skull. Several pins are normally used to engage the skull, resulting in increased ability to control the force vectors of the traction force. Force is applied to the halo ring by means of two hooks which attach to the halo ring on either side of the head in line with the longitudinal axis of the spine. These hooks may be moved forward or rearward to control flexion and extension torques on the skull in the anterior-posterior plane. Further, the halo may be attached to a plaster body cast or a vest type structure with a supporting linkage to allow traction to continue while the patient ambulated. This mobility was the principal advantage of the halo ring, although another advantage exists in that there is no movement between the skull and fixation pins, which reduces the chance of infection of the scalp in the areas surrounding the pins.
Because the halo completely encircles the head, it is necessary during application that an assistant gently lift the patient's head from the stretcher or support the head off the end of the table to provide sufficient space for the ring to be positioned around the patient's head.
Generally, the halo ring is placed just above the external ear. Pins are inserted through threaded holes spaced around the ring and diagonally opposite pins were tightened simultaneously using torque screwdrivers. The pins are then locked into place with set screws.
A disadvantage of the halo is that x-ray films of the pin location in the skull are difficult to obtain and give deceptive images, unless the x-ray was made of each pin at an angle tangential to the skull at the point of entry of the pin. The halo type ring also generally leaves pin hole scars over the eyebrows because the anterior placement of the pins is generally in the forehead region.
An improved orthopedic traction tong apparatus disclosed U.S. Pat. No. 4,444,179 to Trippi, comprises the combination of a generally arcuate main support member which extends from one side to the other side, over the top of the head of the patient user of the device. Means located generally in the central portion of the arcuate support member are provided to apply tension at any predetermined angle, as measured with respect to an imaginary axis line extending vertically upward through the center of the head of the user patient when the tongs are in use, the vector angle being in the side-to-side relationship to the head of the user patient. The tension applying means also includes means for connecting the tongs to a source of tension at any predetermined angle, measured, when in use, with reference to the imaginary axis line, front-to-back of the head of the user patient.
A pair of pin support means are secured at each end of the arcuately configured main support member for securing cranial pins to the orthopedic traction tongs. Each of the pin supports comprises a generally arcuate member extending from an end of the main support member and partially around the head of the user patient for permitting cranial pins to be inserted into the skull at radially spaced intervals around the head of the user patient. The relationship of the main support means is therefore fixed with respect to the head of the user.
The fixation rods are secured to respective ends of the main support and to fix the position of the traction tongs with respect to a vest or other external supporting means structure, thus enabling force to be applied through the rods to the main support means. Each rod connecting means comprises a pair of relatively rotatble clamp elements and means for securing the clamp elements to each other in a fixed relationship for applying force and tension to the head of the user patient at a preselected angle. The rod connecting means may be secured to the fixation rods at different positions on the respective side of the user's head, and apply tensile force through the tongs to the head at a preselected position.
The entire disclosure of U.S. Pat. No. 4,444,179 to Trippi is hereby expressly incorporated herein by reference.
Even with the improvements achieved by the Trippi device, there are still difficulties encountered in cervical traction applications. Such devices are sometimes difficult to accomodate to a certain head sizes; and, since the pin support means are fixed relative to the main support member, it is not always convenient to place the cranial pins in desired locations to avoid interference with x-rays and to secure the pins in intake portions of the patient's skull. Accordingly, there is a need in the art for an improved cervical traction apparatus which provides universal adjustment of the position of the pin support means relative to the main support so that a position may position the cranial pins carried by the cervical traction apparatus at optimum locations for treating the patient.